This invention relates generally to closure structures positioned in an opening, such as a doorway, and is particularly directed to apparatus disposed about an opening for engaging a body positioned within the opening in a sealed manner, such as a loading vehicle positioned in and extending through a warehouse door opening.
In the loading or unloading of a vehicle through an opening in a wall such as of a warehouse, it is frequently desirable to isolate the interior of the warehouse from the elements outside. For example, for the comfort and safety of the loading/unloading personnel it is frequently desirable, and perhaps essential, to isolate the outside elements of heat, cold, rain, snow, etc., from the working environment within the warehouse during the transfer of goods to or from the vehicle. Security reasons may also necessitate closure of the space between the doorway and the vehicle.
Prior art structures for providing such a seal have involved movable structures which extend outward from a wall of the warehouse and inward toward the center of the doorway in the wall. Such structures are typically termed "dock seals" and may involve fixed peripheral structures about the doorway or an inflatable structure adapted to engage the side of a rail car or end of a trailer positioned adjacent to the warehouse wall. Examples of inflatable dock seals can be found in U.S. Pat. Nos. 3,303,615 (a single elongated inflatable tubular member mounted to adjacent outer and inner corner sections of a building opening); 3,391,503 (interconnected top and side elongated inflatable tubular members affixed to a building wall adjacent to an aperture therein and extending outward from the wall); 4,262,458 (four interconnected inflatable members disposed about a rectangular aperture in a wall for extension outward from the wall when inflated); and 4,389,821 (an inflatable dock seal wherein the three seal structures move outwardly from the wall and towards one another when inflated).
These and other prior art dock seals generally involve a complicated mechanical and pneumatic arrangement which is highly subject to deterioration by the outside environment as well as damage from a misaligned vehicle attempting to back up into the wall opening about which the dock seal is disposed. In particular, those arrangements which extend inwardly from the sides of the aperture tend to extend substantially into the aperture even when retracted making them particularly susceptible to engagement and damage by a moving vehicle and only provide limited sealing engagement with a vehicle.
The present invention overcomes the aforementioned limitations of the prior art by providing an air perimeter seal for an opening which is adapted for tightfitting, sealed engagement with an object such as a vehicle positioned within the opening. The air perimeter seal is comprised of an upper and two side accordian-like flexible and inflatable sections which are coupled together and are further coupled to a source of air under pressure such as a blower. The three inflatable sections are particularly adapted for positioning on the side and upper edges of a rectangular door opening and for engaging a loading vehicle positioned within the door opening.